Pressure balanced door



Oct. 29, 1968 w. w. BIRD PRESSURE BALANCED DOOR 4 Sheets-Sheet 1 Filed March 1, 1967 IN VEN TOR.

WALTER W. BIRD 63M, @wmwm ATTORNEYS Oct. 29, 1968 w. w. BIRD 3,407,534

PRESSURE BALANCED DOOR Filed March 1, 1967 v 4 Sheets-Sheet} INVENTOR.

WALTER W. BIRD BY vATTORNEYS Oct. 29, 1968 w. w. BIRD PRESSURE BALANCED noon Filed March 1, 1967 4 Sheets-Sheet 3 INVEMTOR.

WALTER w. BIRD BY GMM,M.@ A TTOR/VEYS Oct. 29, 1968 w, w, 5mg 3,407,534

PRESSURE BALANCED DOOR Filed March 1, 1967 4 Sheets-Sheet 4 lNvENT'R.

WALTER W. BIRD BY A r TOPNEYS United States Patent Ofice 3,407,534 Patented Oct. 29, 1968 3,407,534 PRESSURE BALANCED DOOR Walter W.

' Structures, Inc., Buffalo, N .Y.

Filed Mar. 1, 1967, Ser. No. 619,829 Claims. (Cl. 49-68) ABSTRACT OF THE DISCLOSURE Brief summary of the invention This invention is directed in particular to the art of air inflated structures which depend upon internal air pressure to retain their structural integrity. In such an arrangement, it is desirable to minimize the loss of internal air incidental to door opening and closing action. With regard to this, the present invention is concerned with an airlock assembly.

A further problem and one which does not relate to the airlock is the provision of emergency door exits required by ordinance. Usually, the requirements necessitate an outwardly opening door which operates with a minimum of effort or manipulation. In an internally pressurized environment, it will be appreciated that an emergency door raises certain problems. For example, the door when closed will be subjected to considerable opening force due to the internal pressure. If this internal pressure is counterbalanced by a spring of sufiicient strength to overcome the pressure, the door will be exceedingly diflicut to open beyond that point at which the internal pressure ceases to exert any substantial door opening effect. On the other hand, a door held closed-by a conventional panic lock will, when released, fly open and will require substantial effort to reclose.

The present invention involves basically an arrangement in which the internal pressure itself is used to hold the door closed and which tends to counter-balance the internal pressure against the door at and near the closed position.

It is a primary concern in connection with this invention to provide an improved form of door and means associanted with the door ad acted upon by differential fluid pressure serving to return or maintain the door in its closed position against the difierential fluid pressure a'cting thereagainst. Y

Another object of this invention is to provide an improved structure as aforesaid incorporating a door and a movable vane, both operated upon by differential fluid pressure, there being link means joining the door to the vane and effective therewith to increase the door-closing force as the door is'moving toward its closed position and vice versa.

Another object of this invention resides in the provision-of an improved structure as aforesaid wherein the link means is in the form of pivotally interconnected strut members and a reaction member normally allowing the strut members to reside in over-center relation to thereby constrain the strut members to act as a compression Bird, Williamsville, N.Y., assignor to Birdair restrained fashion so as to substantially completely destroy their compression or tension transmitting efiect, all to the end that the door and vane are interconnected for conjoint movement only in that region of movement of the door where it is at or near its closed position.

A further object of this invention is to provide an assembly according to the preceding object wherein spring means is associated with the strut members to cooperate with the aforesaid over-center strut arrangement to provide a return force on the door which does not abruptly terminate when dead center is passed.

Another object of this invention is to provide an improved airlock structure incorporating door assemblies as above described.

Other objects and advantages of the invention will appear from the specification hereinafter and the accompanying drawing-s, wherein:

FIG. 1 is a horizontal section taken through an airlock structure and a portion of an adjoining building constructed in accordance with the present invention;

FIG. 2 is an enlarged horizontal sectional view illustrating the details of the link means according to the present invention;

FIG. 3 is a horizontal elevational view taken substantially along the plane of section line 33 in FIGURE 2 showing further details of the link means;

FIG. 4 is a vertical section taken substantially along the plane of section 44 in FIGURE 1 and illustrating the vent means for the chambers housing the vane members;

FIG. 5 is a vertical elevational view taken substantially along the plane of section line 55 in FIGURE 1 illus trating the mounting of one of the doors; and

FIG. 6 is a vertical elevation taken substantially along the plane of section line 66 in FIGURE 1 showing the air access door mounting arrangement.

In What follows, the basic concept of a pressure balanced door is described in conjunction with an airlock assembly. 'It is to be understood, however, that an outwardly swinging emergency door separate and apart from any airlock feature may be installed by simply mounting one of the airlock doors at a suitable site in the building. In such a case, no external handle would be provided on the door whereas it is easily opened from inside simply by pushing against it. The amount of force required is minimal but, at the same time, the door will automatically close when released.

With reference at this time more particularly to FIG- URE 1, the reference character 10 indicates in general a building construction which may taken any desired form such as for example it may be in inflatable type of building construction maintaining its shape and structural rigidity by virtue of internal air pressure to which the enclosure defined by the building is constantly maintained, as will be understood by those skilled in the art. The reference character 12, on the other hand, indicates in general an airlock assembly constructed in accord with the principles of this invention. The airlock assembly pro vides means for entrance and egress and defines a secondary enclosure 14, as distinct from the enclosure 16 defined by the building structure 10, the secondary enclosure being adapted in a manner hereinafter more particularly pointed out, to isolate the building enclosure 16 from ambient atmosphere and minimize leakage of internal pressurizing fluid from the interior of the building 10 during entrance or egress.

. The airlock structure 12 consists essentially of oppositely disposed side walls 18 and 20, a top wall 22 (FIG- URES 46), an inner end wall 24 having an access opening and hingedly mounting, as by a suitable frame member 26 and associated hinge 28, an access door 30 for the interior 16 of the building 10 and swingable inwardly into the airlock structure 12, as indicated by dashed lines in FIGURE 1. The airlock structure 12 also includes an outer end wall 32 provided with an access opening and hingedly mounts an exterior door 34'which swings outwardly as shown, the structure having a suitable jam member 36 and associated hinge 38 mounting the door 34, substantially as is shown.

The airlock structure also includes first and second chambers 40 and 42 defined between the outer wall structure 44 and the wall spaced therefrom and by the associated top wall 22 and the corresponding inner wall members 46 and 48. The chamber is vented to the interior of the building 10 as by foraminous member 50 (FIGURES l and 6). The second chamber 42 is similarly vented but to ambient atmosphere by means of the foraminous means 52 (FIGURES 1 and 5).

The operation of the airlock structure is, in general, quite conventional, That is to say, the building structure 10 is subjected to some internal fluid pressure which is greater than the ambient atmosphere exterior to the building and the airlock structure 12. The interior 14 of the airlock structure 12 will normally be at ambient pressure so that a ditferential pressure will be acting upon the access door 30. This differential in pressure will tend to open the door 30 and permit the fluid to escape from the interior of the building into the airlock structure 12. This invention concerns means for preventing this from occurring. Similarly, should the interior 14 of the airlock structure 12 be subjected to the same pressure or substantially the same pressure as the interior 16 of the building 10, as when a person leaves the interior of the building and enters the airlock structure 14, thus inescapably pressurizing the interior 14, a differential pressure will then be acting upon the exterior door 34 tending to force this door open. This invention also concerns means for preventing this from occurring relative to the exterior door 34.

Reference will be had now to FIGURES 2 and 3 to illustrate the details of the means for preventing unwanted motions of the door 30. In these figures, it will be noted that the inner side of the door 30 is provided with a mounting bracket member 56 having an outstanding car 58 fixed thereto. A pair of link members 60 and 62, joined as by the fastener 64 and intervening spacer 66, straddle the car 58 and are pivotally joined thereto as by a shaft member 68. A pair of torsion springs and 72 have each one end thereof received in a notch in a respective end of the shaft 68 as is clearly shown in FIGURES 2 and 3 and the opposite ends thereof are provided with hook portions 74 and 76 which engage over the members 60 and 62 serving normally to urge these members in a counterclockwise direction when viewed as in FIGURE 2, the purpose of which will be presently apparent. Obviously, the shaft 68 must be fixed to the ear 58 to prevent rotation of the shaft 68. A link pin 80 is carried by the free ends of the members 60, 62 and a further member 82 is pivotally joined to the members 60 and 62 in the manner indicated most clearly in FIGURE 3. The free end of the member 82, in turn, carries an eye member 84 which may have a threaded stem 86 engaged with the member 82 for adjustment purposes. The eye 84 engages a pivot pin 88 carried by the cars 90 of a bracket 92 fixed to one side of a vane member 94, see particularly FIGURE 2. The vane 94 is hingedly mounted as at to the airlock wall 20 and is located within the chamber 40 it being seen, from FIGURE 1, that the free edge of the vane 94 swings in close proximity to the wall member 46 which is arcuate as shown.

Thus, the vane 94 effectively divides or partitions the chamber 40 with one side of the vane 94 being communicated with the interior 14 of the airlock structure bygratings 104, see particularly FIGURE 4, and with the outer side of the vane 94 communicating with the interior of the building 10 through the grating; or foraminous means 50 previously described. Thus, there is a differential pressure acting on the vane 94 which will be the same as 4 the dilferential pressure acting upon the access door 30.

The link member 82 carries a bracket 106, see FIG- URE 2, which in turn mounts a roller member 108 adapted to bear against a cam plate member 110 fixed to the wall 20 of the airlock, substantialiy as is shown. As is clearly illustrated in FIGURES 2 and 3, the links 60, 62 and 82 are in an over-center relationship when the door is closed (full line position). The purpose of the roller 108 and cam 110 is to allow this over-center position as shown, but to move the two links when ultimately passed over-center position as the door is first swung toward open position and vice versa. As previously described, the springs 70 and 72 normally urge the link 60, 62 counterclockwise as shown in the drawing and when the roller 108 has passed beyond contact with the cam plate 110, the springs 70 and 72 tend to prevent the two links from buckling. The ditferential pressure acting on the vane 94, however, exerts sufiicient force on the vane which resists movement thereof as imparted by the links so that a buckling action does take place as is shown in dashed lines. The net result is that the movement of the vane 94 is substantially uniform with respect to the door 30 only at the very beginning of door opening movement. The vane 94 passes through only a short are before further motion is arrested. By this time, however, the over-center relation of the links is broken and continued opening of the door causes further buckling of the links and is resisted only by the action of the springs 70, 72, the roller simply pivoting away from the cam plate about the thenfixed pivot point 88. This is illustrated in FIGURE 1 by full and dashed lines for the components under consideration.

During the initial movement of the door, it will be clear that the links 60, 62 and 82 are acting really only as a compression strut, substantially as if they were rigidly joined and not articulated by the member 80. Once, however, the dead center position is passed, the action of the springs 70 and 72 takes over. The net result is that while the door is near the region of being closed, the movements of the vane 94 and the door 30 are substantially uniform and, therefore, the greatest door-closing force is exerted. There again, the door closing force progressively diminishes as the door is continued to be moved toward its open position. This counteracts very closely the forces acting on the door due to differential pressure and still leaves a net return force acting on the door to close it when released. The action is, of course, reversed when the door moves toward closed position and assures that the door will be positively closed to minimize leakage of the internal pressurized air.

The same action applies for the door 30 and its associated vane 130. The chamber 42 contains a vane hingedly mounted as at 132 and the opposite sides of this vane are communicated respectively with ambient atmosphere through the grating 52 previously described and the grating means 134 on the wall structure 20, see particularly FIGURE 4. As before, the free edge of the vane 130 runs in close proximity to the arcuate wall portion 48 in part defining the chamber 42. As was the case in conjunction with the door 30, the door 34 is provided with a bracket 136 which mounts the link means 138. The link 138 corresponds to the members 60, 62 of FIGURES 2 and 3 whereas the link 140 corresponds to the link member 82 of FIGURES 2 and 3. The vane 130 is normally disposed in the full line position shown in FIGURE 1 as opposed to the normal full line position of the vane 94. The cam plate 142 for the roller assembly 144' carried by the link 140 is mounted on a suitable post or support member 146 which is, of course, fixed and stationary. The operation as between the door 34 and the vane 130 is in all of the respects, identical with the operation previously described in conjunction with the door 30 and the vane 94.

I claim:

1. A building construction comprising, in combination:

an enclosure subjected to internal fluid pressure and having an access opening,

a door normally closing said access opening and hingedly mounted for opening movement relative to said access opening in a direction outwardly of said enclosure,

and means for holding said door closed against the action of fluid pressure thereagainst, said means comprising a chamber communicating both with the interior of said enclosure and with an environment external to said enclosure and of fluid pressure less than the fluid pressure within said enclosure, a vane movably mounted within said chamber and subjected on opposite sides thereof to the internal pressure of said enclosure and the fluid pressure of the external environment, and actuating means joining said access door to said vane for exerting a closing force on the access door which lessens as the door is opened.

2. The building construction according to claim 1 wherein said actuating means comprises two elements pivotally connected respectively to the door and the vane and pivotally connected to each other:

spring means urging said elements to swing toward the door and vane to which they are respectively connected,

and cam means acting on said elements allowing the elements to assume an over-center position when the door is closed.

3. The construction according to claim 2 wherein said cam means comprises a fixed reaction plate, a bearing member fixed to that link member joined to said vane, said reaction plate being positioned for engagement by said bearing member only when said access door is near its closed position.

4. In combination with a door hingedly mounted for movement between open and closed positions:

a fluid pressure operated vane hingedly mounted for swinging movement about an axis closely adjacent the hinge axis of said door,

a pair of elongate links, one pivotally connected at one end thereof to said door and the other pivotally conected at one end thereof to said vane, and said links being pivotally connected to each other at their proximal ends,

an abutment member carried by one of said links,

a fixed reaction plate engaged by said abutment member when said door is closed, said reaction plate being positioned to disengage said abutment member as said door is swung toward its open position,

and spring means acting on one of said links normally urging said abutment member toward said reaction plate.

5. A building construction comprising, in combination:

a building enclosure subjected to internal fluid pressure and having an access opening,

an airlock structure joined to said building enclosure and defining therewith a secondary enclosure communicating with the interior of said building enclosure through said access opening, said airlock structure having an exterior opening leading to ambient atmosphere which is at a lower fluid pressure than the internal fluid pressure of said building enclosure,

an access door normally closing said access opening,

and hingedly mounted for opening movement relative to said access opening in a direction into said secondary enclosure,

an exterior door normally closing said exterior opening and hingedly mounted for opening movement relative to said exterior opening in a direction outwardly of said secondary enclosure,

said airlock structure including a pair of chambers,

each having an opening communicating with said secondary enclosure, one of said chambers having an opening communicating with the interior of said building and the other having an opening communicating with ambient atmosphere, a vane hingedly mounted in each chamber and each such vane separating its respective chamber to isolate the aforesaid openings therein,

link means connecting that vane in said one chamber to said access door and link means connecting that vane in said other chamber to said exterior door.

said link means comprising two elements pivotally connected respectively to the door and the vane and pivotally connected to each other,

spring means urging said elements to swing toward the door and vane to which they are respectively connected,

and cam means acting on said elements allowing the elements to assume an over-center position when the door is closed.

References Cited UNITED STATES PATENTS 1,184,725 5/ 1916 Dawes 49-68 1,842,708 1/1932. Barnes 49109 X 1,941,969 1/1934 Calabrese 49109 X 3,024,796 3/ 1962 Bird 52-2 3,314,198 4/ 1967 Frisk 5 22 FOREIGN PATENTS 14,196 3/ 1907 Great Britain. 1,100,930 4/1955 France.

DAVID J. WILLIAMOWSKY, Primary Examin r.

55 DENNIS L. TAYLOR, Assistant Examiner. 

